What kind of sailing do you like to do? What kind of sailing would suit you best? Each question may supply a different answer but these answers are essential when deciding which is best, monohulls or multihulls.

One, two or three hulls? The matter of whether monohulls or multihulls perform better is a topic for book-length treatments. An online article can only skim the surface of knowledge.

Definitions: by ‘boats’ or ‘yachts’ this piece infers modern production craft for recreational sailing not usually over 40ft overall.

By ‘catamaran’, those with two hulls whose design ‘rafts’ them together, as originally meant by the Tamil word ‘kattu-maram’’: henceforward ‘cat’.

By ‘trimaran’, we imply one central hull and two smaller outrigger hulls, a design extension of the catamaran derived from that word, which has been in use since the 1940s. Referred from now as ‘tri’.

Comparing like with like is a little impossible in this case. A nuclear submarine is good at delivering lethal weaponry, but few would say it’s great at stowing its anchor.

The go-to expert, PBO contributor Gavin Le Sueur says: “I’m never a fan of comparisons, we are all bums on the water out there for the adventure.”

For detailed information, Dr Le Sueur’s Multihull Seamanship (Fernhurst Books, 1997) is highly recommended, and it’s worth being mindful of his advice.

“All yachts are the same: performance comes down to weight, hull lines, lateral resistance, sail quality and trim, and helmsman skill. There are so many types of hulls in both monohulls and multihulls that the question is an entire textbook to answer.”

Sailing performance

If you’re a sailor keen on the thrill of speed, then multihulls will hold a strong attraction. Cats and tris generally have higher top and average speeds.

Velocity is regarded as the primary attribute of multihulls. With shallow draught and light hulls, multis can gather way, and therefore speed, in the lightest breath of wind.

You may desire speed in a sailing boat, but will it be too difficult to manage?

Ease of sailing might be a greater factor than speed. Performance-wise, there are good arguments to say cats are easy to sail.

A voice in agreement is Martin Thomas, who operates the Solent Sail charter business and RYA sea school with a Gosport-based Nautitech Open 40 cat.

“Most cats can’t sail as close to the wind as a mono,” says Thomas. “But they’re faster off the wind and that can make them faster overall.”

Dealing with fewer masts might make things less complex. Multis tend only to have one mast.

Comparing a tight mono cockpit well against a squarish cat with trampolines, the multi has a far bigger working area to manage the sails. Angles of sheeting may well be shallower. A flatter work area makes reefing easier.

Configurations of sail plans on multis and monohulls are hard to compare.

But to generalise and simplify, a multi with a lower mast than a monohull will tend to fly more sails.

A lower-aspect rigged tri can trim sails in a sleek sequence and make good use of the slot effect for speed.

Cutter-rigged tris might find a yankee and staysail quicker and more adaptable than a big genoa.

Cat forestays are under less tension than a mono or tri but foredeck crew have got more space to manoeuvre.

“Cats don’t need a pole,” explains Thomas. “You can fly it with a guy from each bow. Gybing the spinnaker is therefore much easier.”

Multis experience higher apparent wind, sucking more wind forward with their speed. The speed of a multi favours flatter cut sails.

Multis have more leeway than monos because they have more apparent wind.

Multi crews going faster downwind than monohulls consequently feel apparent wind that much less. They can feel no wind at all when surfing downwind.

By extension, acceleration and deceleration are not so recognisable.

If you’re the type of sailor who likes the big physical signposts about points of sail, for instance, the tipping one’s head towards the boom, or the slide and crash of ill-stowed galley mugs, when coming up hard on the wind in a monohull, then multis might not offer that ‘ease’ of handling.

Closer-winded, monohulls roll into a tack with a flip of the boom. Multis in general are slower, with commensurate less force in the rig.

Turning multis through the wind is friendlier for those sailors wanting a possibly less sudden or even violent manoeuvre.

Multis take longer to turn more of an angle. The exception is racing multihulls with comparatively good pointing ability.

Generally, a slower-to-tack multi has a proportionately greater risk of being ‘in stays’, losing way when pointing to the wind.

The chance of staying stopped though, is perhaps less, as multis can gather way astern, indeed very smartly.

Sailing backwards briefly and skewing round (as a land vehicle does during a three-point turn) into the new tack, is easier on a multi.

Beware the greater forces on generally smaller rudders, however. But diminutive cat rudders retain more verticality than their monohull counterparts.

Rounding up or broaching is less likely with that grip on the water. Gybing multis can feel almost leisurely in comparison with monos.

This isn’t to say the boom doesn’t need managing across in high winds, being centred then eased as the stern goes through the wind.

Sail performance theory, however, is less a consideration if you’re contemplating chartering a multihull for cruising, say in warmer, non-tidal waters.

Ian Walker, twice double Olympic silver medallist and winning skipper of the 2015 Volvo Ocean Race, now UK general manager of North Sails, says you don’t generally charter a cruising multihull for its sailing performance.

Walker has chartered cats for family breaks in Greece. Who better to ask about going from performance monohulls to cruising cats?

“The boats I have sailed have been OK at covering distance [by] reaching,” he says. “But they tacked through very wide angles upwind with lots of leeway (no boards) and they were under-canvassed downwind. We ended up doing a lot of motoring and often wondered why we
had the mast at all. You do not get the enjoyment of feeling the balance on the boat like you might on a monohull.”

Motion

Only you can answer whether you’re the type of sailor who, as Walker says, ‘enjoys feeling the balance’.

If being off-balance makes you miserable, it’s time to buy a cat. They don’t roll.

But, warns Martin Thomas of Solent Sail, “their motion can be a little erratic”. Multis do pitch, but less so generally than monohulls.

There’s a whole field of naval architecture being passed over here. The effects of wave action on design. If the bridge deck of your cat arches upward from the hulls, waves are more likely to pass under unheeded.

A beamier cat will avoid the two bow waves meeting underneath.

Speed is a complication to the motion factor. A speedier vessel, whether mono or multi, will invite more rolling, pitching, surging, swaying and heaving than a slower one.

Vessels more prone to acceleration and deceleration will be more prone to those sudden movements, resulting in slamming or jerking. Multis are not more twitchy than monos.

It’s rather multis lack that inertia which damps things down for mono sailors, rolling in their ‘sea-kindly motion’.

Movement aside, a lesser factor in seasickness is said to be how much you can see.

Visibility

Do you have a better view from the helm? Designs vary. The latest cats offer panoramic views which are usually popular with children.

In one aspect, multis demand more visibility because of speed.

The Colregs alert us to the danger of another vessel on a constant bearing.

However, it is the decreasing range portion of the rule which is more relevant to multis.

Arguably you’ll be closing a large ship much faster than a mono.

When selecting his cat, Martin Thomas had to choose between four options for placing the helm.

A forward position (for example on the Gunboat) has a good protected view, near lines at the mast base, but visibility is restricted to the side decks for mooring.

Lagoon 52s offer a great horizon from a full flybridge but you’re more exposed and the boom has to be higher.

A Lagoon 42 with a helm halfway up one side is a more restricted position with a good view forward.

Thomas plumped for the aft quarter position on his Nautitech 40.

“At first, this was not my choice for visibility. Actually, it’s not too bad as you can see under the sails and the view of the main is the best. Best of all, you’re on the same level as all your other guests and closest to the side deck for mooring.”

Accommodation

Cats are hard to beat if you’re a sailor for whom accommodation is paramount. Tris usually don’t have enough space in their outriggers for berths so compare with monos on this count.

Cats are roomier than monohulls. The space feels more sheltered. Stowage options are greater.

Lee-cloths in general aren’t called upon in multis and don’t break up the space.

“If it’s raining,” says Martin Thomas, “you don’t have to sit in your foul weather gear in the cockpit, just go inside. Similarly, if the sun is beating down, you don’t have to get burnt, just go into the shade.”

Privacy is greater than on a mono. David Lewis, whose Rehu Moana was the first cat to circle the world, was accused of having his wife in one hull and his lover in the other.

Cats will always win over monohulls when it comes to living space, but as Gavin Le Sueur adds: “If you get twice the room and it costs twice as much is it a win?”

Martin Thomas says his four cabins are “all well separated from each other. You don’t tend to overhear noise from one cabin to another.”

For Ian Walker, space is where catamarans score highly… “Not because the cabins are huge – they are not – but because cruising with two families you can take one hull each. Kids in the bow, adults aft and bathroom/heads in the middle. Extras or anyone who can’t sleep can always go on deck or in the main saloon. Everyone has their own space and you come together to socialise and sail. Catamarans have huge amounts of space for socialising often both indoors or out.”

Moving from accommodation to space in general, it’s worth noting the roof of a cat forms a broad platform to lay solar panels.

Renewable electricity can also be generated from the flat roof of a larger aft targa bar than monos.

This is generally a larger permanent davit for a ready-to-launch tender, and there’s space for kayaks, SUPs… and unicorns.

Manoeuvrability

Hull design, cross-section, beam, draught, flare, sheer, tumblehome… all these factors inform how monohulls or multis move.

Choosing between them will mean evaluating them all and there’s not space here for that.

More beam supplies more buoyancy, and a shallower draught will surf downwind but slam upwind (in general).

For Ian Walker, a cat under sail isn’t great. “One of my biggest surprises is actually how manoeuvrable a catamaran is under engine. Coming from a monohull background I didn’t appreciate how powerful it is to have two engines/propellers. This meant I could turn the boat in its length in a marina – something you could never do with a monohull. Having said that, you do need a bit more space!”

Cats with outboard engines on each hull sometimes require a longer shaft to get the prop low enough for traction in the water.

A consequence of greater average speed on a multi is the greater force on an unfolded prop.

Folding props are more common on multis. Foils tend to be stronger. A tri will generally only have one centreboard. Cats sometimes have two daggers or centreboards in each hull.

Each needs to be stronger than a mono, in general, because of greater leeway.

Stability

Ask yourself what you understand by ‘stability’. It’s a huge subject. As mentioned, multis don’t heel. (A tri does a bit, but not much.)

Clearly, if heeling upsets you, you’ll feel far more secure in a speeding cat than in a mono. But on a tri with outriggers that aren’t so buoyant, and you’re watching the leeward one starting to submerge, will you feel safer than in a mono?

Cats don’t heel due to their beam but then there’s less prior notice, when it comes to it, of being knocked down.

Multis deliver on level upright sailing. Being flat allows sails to draw correctly.

It follows that there’s less effort to balance or move ballast. A cook preparing food requires no gimballed oven if the hull never tips or lifts from the water.

Ian Walker describes the lack of heel as “a major plus for less confident sailors”.

Perceived stability is, he argues, “equally valuable when at anchor or under sail/engine. I have never put ultimate stability to the test as I don’t think the charter companies would have forgiven me… flying a hull would definitely be frowned upon.”

Storm handling

Design factors again dictate storm handling. Cats don’t have keel-stepped masts but their beam helps them stay flat in swell.

Faster boats can outrun or keep up with wavesets. Multis might be easier to surf. Breaking waves can pass under a cat’s central portion.

Cats and tris can surf ‘belly down’ as it were.

For Martin Thomas, multis are “far better” than monos downwind in heavy weather.

Lying a-hull with heavy seas on a quarter, a cat can sometimes skid sideways from a beam wave. Thomas says he’d always be running rather than lying a-hull or heaving-to in a cat.

Running on a quartering sea in a multihull is fast with little or no jerking motion. A cat can even have its hatches open in high winds.

The same could go for a tri hull, although hatches in outriggers are notorious for leaking.

Multis offer more stress points for heavy seas to test, namely at the junctions where beams meet hulls or outriggers.

Compression and tension go right across these fittings. Wave action and windage on higher cat topsides are a factor in heavy weather.

“I have only experienced a few squalls in a cruising catamaran,” says Ian Walker. “I’d be concerned about flipping a catamaran in storm seas and would avoid this if I could. High windage and no keel means you need to allow for wind in all manoeuvres.”

A wide boat has initial stability but multis are not self-righting beyond 75°. Deep-keel monohulls can roll upright again.

It follows that multihull sailors are more conservative in making manoeuvres that might ultimately carry the risk of capsizing.

Being slower to tack, for example, is to be more exposed.

For tri sailors, having a portable bilge pump to clear an outrigger of water is regarded as essential.

But generalisations about storm handling are unwise, says Gavin Le Sueur. “A 60 ft racing mono and a 60 ft racing tri or cat have different survival techniques that require specific seamanship management. No two storms or two boats are the same, no matter what the type.”

Flotation

Once you’ve turned turtle in a multi, it’s universally assumed you have no chance of righting again. Yet they are very stable upside down.

A tri has some redundancy; a ‘hull’ can be ‘let go’. A trailer-able folding trimaran can (in principle) contract its ‘wings’ while inverted.

Depending on where the centre of buoyancy and the centre of gravity are located, multis can – in theory – be righted.

Inflatable bags can change the equation. Heaving over an inverted liferaft on a sea survival course gives an appreciation of the practical difficulties of ‘breaking the surface tension’ and other factors.

A cat can be turned upright again in pitchpole fashion by pulling the two bows up and out with a bridle.

If none of this works, multi sailors are satisfied that their lighter vessels take much longer to sink than monohulls, even if every upturned hull is flooded.

Anchoring

A night at anchor is a less rolly affair in a multi. A lighter hull would imply less weight for the anchor and chain.

Cats require a bridle to centre an anchor which runs forward; tris don’t need this. Cats can anchor from the quarter, although there will be windage.

“Multis are more wind than tide affected,” says Gavin Le Sueur.

Monohulls at anchor lie to the tide, but higher topsides and thus greater windage on a multi can make it lie athwart the stream, or even blow forward over the anchor chain, so much that there is a risk it can wrap around centre- or daggerboards.

Picking up a mooring buoy can be tricky in a multi if ‘first contact’ isn’t outboard of a hull.

Travelling over it is as inadvisable as sailing right over a lobster pot.

For anchoring, Ian Walker advises “to get organised with a bridle which prevents you from ‘sailing’ over the anchor chain and chafing the hulls… shallow draught means you can often anchor much nearer the beach. It’s satisfying being late into a popular anchorage and stealing the best spot in shallow water where the monohulls can’t go!”

Berthing

One thing Martin Thomas admits he didn’t think about when he first bought a cat was that some locked marinas are inaccessible due to the beam of the lock.

“Port Solent is OK, Birdham Pool is impossible, Chichester is just about OK with a lock width of 7.1m compared to our beam of 6.9m.”

The downside to berthing for multis is that some marinas charge a premium.

A folding trimaran, though, could sneak up into a single berth.

Martin and Ian are both quick to say that having two engines several metres apart is a great assistance when manoeuvring a cat inside a marina.

They love being able to turn a boat in its own length, with one engine going forward and the other astern. No springs are needed.

Taking the ground monohulls –generally – need bilge keels or legs but all multis take the ground.

As shallower anchorages are opened up, so too are drying ones. Impromptu hull inspections are on the face of it straightforward.

That said, stub keels can present complications. Mud in centreboard or daggerboard casing is a factor, and windage as soon as you refloat ought to make you aware of dangers within the swinging circle of a kedge.

Costs

Are you chartering in the Mediterranean or owning in tidal waters?

The cost of ownership is not something Ian Walker admits he’s ever considered – because he’s always chartered.

A summer week in Italy does not mean you have to consider a larger-than-usual crane (with spacer bar) for an annual lift-out.

Chartering a multihull swerves the issue of incurring two servicing costs for two engines. Then again each engine will be smaller, usually, than its mono counterpart.

Rigging, hatches… “Two hulls, two jobs,” Gavin Le Sueur is fond of saying.

A 40ft multihull is generally more expensive than a 40ft monohull. But then if you can fit two families in one boat for a charter, on a cat with 14 berths.

Martin Thomas says he uses a lot less fuel with a cat “as it tends to sail faster than it motors.”

Mono wins over multi on cost, says Gavin Le Sueur, by virtue of being cheaper.

Sail, hull and electrical maintenance costs are much the same but mooring, slipping, marina and antifouling costs are usually higher for a multihull.

Personal choice

To generalise: sail any boat you deem to be up to the conditions you want to sail in.

Catamarans suit Gavin Le Sueur’s style of sailing. Martin Thomas would pick a cat over a monohull, “though it’s not always an obvious choice.”

Two cat sailors come down in favour of cats, so what’s new?

To decide for yourself, read books for a proper treatment of the subject.

Monohullss and multis have both given Ian Walker much fun.

To him, then, a last word: “Having had some amazing holidays cruising on cats it would take some persuading to get my wife to now charter a monohull, especially if we were with another family. Personally, I’d prefer the sailing on a monohull. But for comfort, space, socialising, anchoring, swimming, sunbathing on the trampoline etc, then it’s a catamaran every time. Maybe if I could get my hands on a high performance catamaran I might be happier with the sailing but I suspect my wife might not wish to come with me.”

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